GB1215706A - Adjustable french curves for circular arcs - Google Patents

Abstract

1,215,706. Drawing-appliances. D. HAEFELE. 19 Dec., 1967 [21 Dec., 1966], No. 57735/67. Heading B6P. An appliance, stated to be for drawing circular curves, comprises a rigid rule 1 with a groove 3, the shape of which is defined by a given equation, and a slide member 4 consisting of a flexible guide rail 6 slidably engaging the groove 3 and a number of resilient transparent strips 5 which are attached to one another and to the guide rail 6 so as to be slidable lengthwise relative to one another. As the slide member 4 is moved along the rule 1, its inner and outer edges assume the shapes of circular curves, the radii of which are indicated by a marker line 7 on the slide and graduations 2 on the rule 1. In making the slide member 4, the assembly of strips 5 is cut along a line which, if the member 4 was placed in position A with the long sides tangential to the groove 3 at a reference point where the radius of curvature of the groove is infinity, would lie along the line of the groove. The rail 6 is inserted between the two parts so formed and the strips 5 are welded to the rail at the narrow end of each part, and are connected together by any suitable means which allows of lengthwise sliding of the strips on one another. In one modification (Fig. 5), the two parts, of the member 4 are slidable along the two edges of the rule 1 and in another modification (Fig., 4), the member 4 is arranged below the rule 1.